Well, no, it's his wife's plane. The New York Times tries to gin up a controversy, but as they admit, there's nothing to it:

The senator was able to fly so inexpensively because the law specifically exempts aircraft owned by a candidate or his family or by a privately held company they control. The Federal Election Commission adopted rules in December to close the loophole — rules that would have required substantial payments by candidates using family-owned planes — but the agency soon lost the requisite number of commissioners needed to complete the rule making.

Because that exemption remains, Mr. McCain’s campaign was able to use his wife’s corporate plane like a charter jet while paying first-class rates, several campaign finance experts said. Several of those experts, however, added that his campaign’s actions, while keeping with the letter of law, did not reflect its spirit.